Synthesis of Hierarchical SAPO-34 by Two Stage Crystallization Process for MTO Reaction
کد مقاله : 1062-INZC6
مرضیه حمیدزاده *1، علی جعفری2، پویا اسدی پور1
1شرکت پژوهش و فناوری پتروشیمی
2پژوهش و فناوری پتروشیمی
چکیده مقاله:
Hierarchical SAPO-34 catalysts were prepared with two stage hydrothermal crystallization procedure. The synthesized catalysts were characterized using XRD, , N2 adsorption–desorption, NH3-TPD,SEM, EDS and FT-IR analyses. The initial hydrogel was first treated at low temperature (110 or 140ͦC) for 3 or 6 hours, followed carried out at high temperature (200ͦ C) for 28 hours. The selectivity of synthesized SAPO-34 catalysts to light olefins and C3=/C2= ratio in the products of the reaction were between 77 to 86% and 0.34 to 0.71, respectively. Increasing in surface area of the catalysts was followed by increasing in selectivity in the reaction. Also Si/Al ratio in bulk of catalysts with same initial gel composition was increased in catalyst treated in low temperature and low time on first stage. According to NH3-TPD, The acidity does not illustrate any specific trend. The results of X-ray diffraction, t- plot and SEM confirmed nanoparticles and oligomers formation from SAPO-34 with inter- crystalline mesopores. The results showed that the samples produced by a two-step crystallization procedure had smaller particle sizes, higher external surface area and narrower particle size distributions than that by an isothermal program.
کلیدواژه ها:
SAPO-34; catalytic properties; crystallization
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